The invention relates to the use of direct current as an aid in healing of defects such as fractures, delayed unions and non-unions in living bone.
Conventional practice for fresh fractures, such as a simple or compound fracture of the tibia, is to apply a long cast and to hope for normal healing within the cast. For a weight-bearing member such as the tibia, the cast may be on the patient for four to six months. Upon removal of the cast, a delayed-union or non-union condition is frequently encountered; and in such event standard practice is to proceed with various options, including bone graft, open reduction and internal fixation (plate and screws), and/or exposure to pulsed electromagnetic fields, as described for example in Ryaby et al. U.S. Pat. No. 4,105,017. For tibia fractures, the number of cases which become delayed-union or non-union cases is at least 30 percent.
Various inventors have addressed the possibility of bone healing through use of direct current. Among these, Brighton et al. U.S. Pat. No. 3,842,841 discloses use of a constant direct current, continuously applied to the region of a fracture or bone defect via a cathode-wire implantation and an anode taped to the skin near the cathode implantation site, wherein constant current is maintained within the range of 5 to 20 microamperes. Levy U.S. Pat. No. 4,026,304 has an extensive discussion of prior art and discloses use of a train of electrical pulses, rather than a direct-current potential, applied to spaced points of an afflicted-bone region via separate wire implantations; the Levy invention was based on various experiments with dogs, involving much surgical invasion. Chiarenza et al. U.S. Pat. No. 4,175,565 discloses an electroconductive dental implant as the cathode for direct-current therapy, wherein the direct current is continuous for relatively short periods not exceeding one hour. And Greatbatch U.S. Pat. Nos. 4,313,438 and 4,314,554 disclose apparatus implanted in the body of a patient for applying direct current in an alternating succession of reversing polarity, to promote germicidal action with one polarity for a period of time, in alternation with promotion of osteogenic action in a succeeding period of opposite polarity.
I have discovered that a high probability of success applies for continuous use of direct current, alone or as a major signal component, in the treatment of fresh fractures of human bone, such as the tibia, and that substantial acceleration of the healing process can occur when direct-current pulses of specifically characterized nature are additively combined with a steady base component of direct current through the site of the fresh fracture.